The transition-metal-free hydroboration of various alkenes with pinacolborane (HBpin) initiated by tris[3,5-bis(trifluoromethyl)phenyl]borane (BArF3 ) is reported. The choice of the boron Lewis acid is crucial as the more prominent boron Lewis acid tris(pentafluorophenyl)borane (B(C6 F5 )3 ) is reluctant to react. Unlike B(C6 F5 )3 , BArF3 is found to engage in substituent redistribution with H...

Silyl and acetyl derivatives of sporopollenin from the pollen of Typha angustifolia L. were prepared. The derivatized products were readily soluble in piperidine-d11 and could be investigated employing one- and two-dimensional proton and carbon NMR (nuclear magnetic resonance) spectroscopy (1H,1H-COSY and 13C,1H-HETCOR techniques). For the first time, a two dimensional 13C,1H-HETCOR NMR spectru...

A homologue series of aliphatic streptomycylamines (SM-amines) have been prepared and tested in vitro (binding to 70S ribosomes) and in vivo (MIC). The short-chain SM-amines act as streptomycin (SM) but are less active than SM. They are inactive towards a SM-resistant Escherichia coli, our strain 042. The long-chain SM-amines are active both towards our sensitive and resistant E. coli, our s...

Nano-copper(0) stabilized on alumina prepared from Cu-Al hydrotalcite has been reported for completely regioselective synthesis of 2,4-disubstituted pyrroles from unactivated terminal aromatic/aliphatic alkynes and isocyanides. The reaction is operationally simple, involves ligand-free inexpensive nano-copper, and affords products in high yields.

Addition of allylmagnesium reagents to an aliphatic aldehyde bearing a radical clock gave only addition products and no evidence of ring-opened products that would suggest single-electron-transfer reactions. The analogous Barbier reaction also did not provide evidence for a single-electron-transfer mechanism in the addition step. Other Grignard reagents (methyl-, vinyl-, t-Bu-, and triphenylmet...

Hydroformylation, a reaction that adds carbon monoxide and dihydrogen across an unsaturated carbon-carbon multiple bond, has been widely employed in the chemical industry since its discovery in 1938. In contrast, the reverse reaction, retro-hydroformylation, has seldom been studied. The retro-hydroformylation reaction of an aldehyde into an alkene and synthesis gas (a mixture of carbon monoxide...

A large set of lowest and medium energy conformers of aliphatic tetramine trien was used to uncover structural-topological preferences of poliamines. Numerous common structural features among HL and H 2 L tautomers were identified, e.g., H-atoms of protonated functional groups are always involved in intramolecular NH•••N interactions and they result in as large and as many as possible rings in ...

[reaction: see text] 1,1,3,3-Tetramethylguanidine (TMG)(1), a nitrogen organic base, is a convenient and useful reagent for chemoselective deprotection of both silyl and acetyl groups on acidic hydroxyl groups such as phenol and carboxylic acid without affecting aliphatic silyl and acetyl groups. The chemoselectivity is dependent on the acidity of the hydroxyl group.